Reaction of terpenes with thiophosphorous acid esters and products thereof



Patented Sept. 14, 1954 OFFlC REACTION OF TERPENES WITH THIOPHOS-PHOROUS ACm ESTERS AND PRODUCTS THEREOF ration of Delaware No Drawing.Application April 21, 1948, Serial No. 22,513

The present invention relates to new compounds having oxidationinhibiting properties and more particularly to the use of such compoundsas oxidation inhibiting additives for hydrocarbon products.

In the development of lubricating oils the trend has been to use moreand more efficient refining methods in order to reduce the tendency ofthe oils to form carbon and deposits of solid matter or sludge. Whilesuch highly refined oils possess many advantages, their resistance tooxidation particularly under conditions of severe service is generallydecreased and they are more prone to form soluble acid oxidationproducts which are corrosive, They are generally less effective than theuntreated oils in protecting the metal surfaces which they contactagainst rusting and corrosion due to oxygen and moisture. They alsooften deposit thick films of varnish on hot metal surfaces, such as thepistons of internal combustion engines.

In accordance with the present invention a new class of chemicalcompounds has been discovered, and these compounds have been found toreduce the tendency of refined lubricating oils and other hydrocarbonproducts to corrode metal surfaces when added in small quantities tosuch materials. These additives are particularly active in reducing thecorrosion of copper-lead and cadmium-silver bearings which are employedin internal combustion engines, and they are likewise effective ininhibiting the oxidation of hydrocarbon products generally andespecially those of petroleum origin.

The new class of compounds forming the subject of the present inventionare bornyl esters of organo-substituted thiophosphorous andthiophosphoric acids. These esters may be conveniently formed byreacting a dicyclic terpene with the organo-thiophosphorous ororgano-thiophosphoric acid such as a diester of dithiophosphoric acid.The reaction is exothermic and is conveniently brought about bycontacting the reacting compounds at normal atmospheric temperatures.The reactants are conveniently employed in a mol/mol ratio, but thereaction will nevertheless take place with any proportions of reactants.Where the product is to be employed as an antioxidant for hydrocarbonmaterials it is desirable not to have present more than one mol of acidfor each mol of the terpene. Whenever either reactant is present inexcess of a mol/mol ratio, which is always the ratio involved in theactual reaction, the excess merely remains as a diluent of the reactionproduct.

6 Claims. (01. 260461) The new class of compounds of the presentinvention may be more accurately defined as the bornyl esters oforgano-substituted acids of phosphorus which have the general formula inwhich R represents a hydrocarbon radical, such as an alkyl, cycloalkyl,aryl, aralkyl, or alkaryl radical, with or without certain substituentswhich may be sulfur, halogens or nitro groups, and such hydrocarbonradicals may also contain ether linkages; that is, an oxygen atom may beinserted at any point in the radical, thus separating the radical intotwo shorter hydrocarbon radicals. Expressed differently, a hydrocarbonradical may be extended by substituting an ether group for a, hydrogenatom. In the above formula X represents oxygen or sulfur, and n may be 0or 1, depending upon whether the acid is a thiophosphorous orthiophosphoric acid.

A preferred subclass of the above esters, readily prepared fromcommercially available materials, consists of the bornyl esters of thedialkyl dithiophosphoric acids. Such acids have the formula where R isan alkyl radical.

The desired bornyl esters of the above defined acids may be formed byreacting the acids with any dicyclic terpene, of which pinene is aparticularly preferred example. Other dicyclic terpenes are camphene andfenchene. Essential oils which contain these materials, such as oil ofturpentine, may be employed in place of the pure terpene compounds.

butyl alcohol, lauryl alcohol, stearyl alcohol, wax

alcohols, alcohols obtained by the oxidation of petroleum hydrocarbons,or by reaction of an olefin, carbon monoxide, and hydrogen by the 3 OXprocess, oleyl alcohol, sulfurized oleyl alcohol, chlorinated andnitrated alcohols, cyclohexyl alcohol, benzyl alcohol, alkyl mercaptans,phenol, alkylated phenols, naphthol, sulfurized phenols, thiophenols,and the like are suitable materials. Also there may be mentionedalcohols containing ether groups typified by ethylene lycol monomethylether, ethylene glycol monohexyl ether, propylene glycol monoootylether, and the like. Such compounds are conveniently prepared byreacting the alcohols with alkylene oxides. Alcohols or phenolscontaining aryl ether or thioether groups may similarly be employed.

The new compounds of the" present invention are particularly useful asadditives for mineral lubricating oils and other hydrocarbon productsfor the purpose of preventing corrosion of metal surfaces with whichthey come in contact and generally for the purpose of inhibitingoxidation and consequent deterioration of the oil. For this purpose, theamount of the additive required is generally from about 0.2 to or evenby weight, relative to the base stock inwhich it is incorporated. Forthe purpose of storage and transportation, it is often convenient toprepare hydrocarbon oil concentrates of the additives containing from25% to 75% by weight of the additive. When it is desired to prepare suchconcentrates, the esters may be conveniently prepared by reacting theterpene and acid of phosphorus in a hydrocarbon medium in concentrationssufficient to produce a concentrate of the desired strength.

The following examples illustrate the preparation of the new compoundsof the present invention and the testing of certain of these compoundsfor their corrosion inhibiting properties when employed in lubricatingoil compositions. It is to be understood, however, that these examplesare not to be considered as limiting the scope of the invention in anyway.

Eroample 1.Bornyl ester of di-n-propyl dithiophosphoric acid A l-liter,3-necked flask equipped with a stirrer, reflux condenser, andthermometer, was charged with 120 g. (2 mols) of n-propanol and 111 g.(0.5 mol) of P285. The temperature rose to 92 C. over a period of about10 minutes. The reaction mixture was then heated at 95 C. for 25 minutesafter which it was filtered to remove a small amount of unreacted P285.The di-n-propyl dithiophosphoric acid thus formed (0.86 mol) was addeddropwise over a period of 1 hours to 117 g. (0.86 mol) of pinenecontained in a 4-necked, l-liter flask equipped with a stirrer, refluxcondenser, thermometer, and dropping funnel. The reaction wasexothermic, the temperature rising from 25 to 38 C. The product was thenheated for 1 hour at 115 C. with rapid stirring. After cooling to roomtemperature it was washed successively with 200 cc. of distilled water,two 200 cc. portions of 10% aqueous NazCOs solution, and. 200 cc. ofdistilled water. The cloudy organic layer was transferred to a 1-literbeaker and blown with nitrogen for minutes at 110 0., followed byfiltration to remove a small amount of insoluble material. A clear,brownish red liquid was obtained, which upon analysis was found tocontain 9.5% phosphorus and 16.9% sulfur.

Example 2.-Bornyl ester of diethyl dithiophosphorz'c acid A l-liter,3-necked flask equipped with a stirrer, reflux condenser, andthermometer was charged with 276 g. (6 mols) of absolute ethanol and 333g. (1.5 mols) of P285. The temperature rose to C. within 15 minutes.After heating for an additional 20 minutes at C., the prodnot wasfiltered to remove a small amount of insoluble material. The diethyldithiophosphoric acid thus formed (2.4 mols) was added to 326 g. (2.4mols) of pinene in a 4-necked, 3-liter flask equipped with a stirrer,reflux condenser, thermometer, and dropping funnel over a period of 1hours, during which time the temperature rose from 25 to 36 C. Theproduct was then heated at 115 C. for 2 hours, after which it waspermitted to stand overnight. The material was then worked u in the samemanner as described in Example 1. A clear reddish liquid was obtained,which upon analysis was found to contain 10.4% phosphorus and 19.3%sulfur.

Example 3.--Bornyl ester of di-(ierL-ociylphenyl) dithiophosphoric acid206 g. (1 mol) of tert.octylphenol contained in a 3-necked, l-literflask equipped with a stirrer, reflux condenser, and thermometer, washeated until fluid (about 0.), after which 55.5 g. (0.25 mol) of P285was added. The reaction mixture was then heated for 1 hour at 145 C.,after which it was filtered to remove a small amount of unreacted P285.To 45.7 g. (0.34 mol) of pinene, contained in a 4-necked, l-liter flaskequipped with a stirrer, reflux condenser, thermometer and droppingfunnel, was added 170 g. (0.34 mol) of the di-(tert-octylphenyl)dithiophosphoric acid, formed as described above, over a period of about1 hour, during which time the temperature rose from 30 to 48 C. Thereaction mixture was then heated at C. for 1 hour. A clear, pale red,very viscous liquid was obtained, which upon analysis was found tocontain 4.6% phosphorus and 9.4% sulfur.

Example -4.Bornyl ester of di-n-propyl thiophosphorous acid A 3-necked,l-liter flask equipped with a stirrer, reflux condenser, andthermometer, was charged with 240 g. (4 mols) of n-propanol and 174 g.(0.5 mol) of P4S7. The temperature rapidly rose to 52 C. After 20minutes, the temperature was raised to C. and held at this point for 2hours. The product, after filtering to remove a small amount of P487,consisted essentially of di-npropyl thiophosphorous acid. To 109 g. (0.8mol) of pinene contained in a 4-necked, 1-liter flask equipped with astirrer, reflux condenser, thermometer, and dropping funnel, was added152 g. (0.8 mol) of the di-n-propyl thiophosphorous acid formed asdescribed above, over a period of 1 hour, during which time thetemperature rose to 45 C. After stirring for 2 hours at 105 0., theproduct was filtered. A clear yellow liquid was obtained, which uponanalysis was found to contain 10.7% phosphorus and 13.2% sulphur.

Example 5.Bornyl ester of di-(sulfurz'zed oleyl) dithiophosphoric acid Amixture of 268 g. (1 mol) of oleyl alcohol and 32 g. (1 mol) of sulfurwas heated for 1 hour at C. with rapid stirring in a 3-necked, 1-literflask equipped with a stirrer, thermometer and reflux condenser. Theclear dark red liquid was allowed to cool to room temperature afterwhich 55.5 g. (0.25 mol) of P2185 was added. This mixture was heated at95 C. for .40 minutes, after which it was filtered to remove a smallamount of unreacted P2S5. To 54.4 g. (0.4 mol) of pinene contained in a4-necked, l-liter flask equipped with a stirrer, thermometer, droppingfunnel and reflux condenser, was added 277.6 g. (0.4 mol) of thedi-(sulfurized oleyl) dithiophosphoric acid prepared as described above,over a period of 1 hour, during which time the temperature rose from 26to 36 C. The product was then heated at 115 C. for 1 hour with rapidstirring. A clear, viscous, dark red liquid was obtained, which uponanalysis was found to contain 3.2% phosphorus and 15.1% sulfur.

Example 6.-Laboratory corrosion tests Lubricating oil blends wereprepared containing 0.25% by weight of each of the products prepared inExamples 1 to 5, using as a base oil an extracted Mid-Continentparafiinic type lubricating oil of SAE 20 grade. These blends and asample of the unblended oil were submitted to a corrosion test designedto measure the effectiveness of the new compounds in inhibiting thecorrosiveness of a typical mineral lubricating oil toward the surfacesof copper-lead bearings. The test was conducted as follows: 500 cc. ofthe oil was placed in a glass oxidation tube (13 inches long and 2%inches in diameter) fitted at the bottom with a inch air inlet tubeperforated to facilitate air distribution. The oxidaticn tube was thenimmersed in a heating bath so that the oil temperature was maintained at325 F. during the test. Two quarter sections of automotive bearings ofcopper-lead alloy of known weight having a total area of 25 sq. cm. wereattached to opposite sides of a stainless steel rod which was thenimmersed in the test oil and rotated at 600 R. P. 1VL, thus providingsufficient agitation of the sample during the test. Air was then blownthrough the oil at the rate of 2 cu. ft. per hour. At the end of each4-hour period the bearings were removed, washed with naphtha and weighedto determine the amount of loss by corrosion. The bearings were thenrepolished (to increase the severity of the test),

reweighed, and then subjected to the test for additional 4-hour periodsin like manner. The results are given in the following table ascorrosion life, which indicates the number of hours required for thebearings to lose 100 mg. in Weight, determined by interpolation of thedata obtained in the various periods.

Example 7.-Chevrolet engine test A blend containing 1.0% of the productof Example 1 in a solvent extracted Mid-Continent paraifinic SAE 10 oiland a sample of the unblended oil base were employed as the crankcaseoil in 36-hour tests with a Chevrolet engine operated at 30 brake H. P.,3150 R. P. M. speed, 280 F. oil temperature and 200 F. jackettemperature. After ,each test was completed, the weight loss of thecopper-lead hearing was determined. The results are shown in the follow"ing table:

The products of the present invention may be employed not only inordinary hydrocarbon lubricating oils but also in the heavy duty type oflubricating oils which have been compounded with such detergent typeadditives as metal soaps, metal petroleum sulfonates, metal phenates,metal alcoholates, metal alkyl phenol sulfides, metal organo phosphates,thiophosphates, phosphites and thiophosphites, metal salicylates, metalxanthates and thioxanthates, metal thiocarbamates, amines and aminederivatives, reaction products of metal phenates and sulfur, reactionproducts of metal phenates and phosphorus sulfides, metal phenolsulfonates, and the like. Thus, the additives of the present inventionmay be used in lubricating oils containing such other addition agents asbarium tert.-octylphenol sulfide, calcium tart-amylphenol sulfide,nickel oleate, barium octadecylate, calcium phenyl stearate, zincdiisopropyl salicylate, aluminum naphthenate, calcium cetyl phosphate,barium di-tert.-amylphenol sulfide, calcium petroleum sulfonate, zincmethyl cyclohexyl thiophosphate, calcium dichlorostearate, etc. Othertypes of additives, such as phenols and phenol sulfides may be employed.

The lubricating oil base stocks used in the compositions of thisinvention may be straight mineral lubricating oils or distillatesderived from parafiinic, naphthenic, asphaltic or mixed base crudes, or,if desired, various blended oils may be employed as well as residuals,particularly those from which asphaltic constituents have been carefullyremoved. The oils may be refined by conventional methods using acid,alkali and/or clay or other agents such as aluminum chloride, or theymay be extracted oils produced, for example, by solvent extraction withsolvents of the type of phenol, sulfur dioxide, furfural,dichlorodiethyl ether, nitrobenzene, crotonaldehyde, etc. Hyrogenatedoils or white oils may be employed as well as synthetic oils prepared,for example, by the polymerization of olefins or by the reaction of.oxides of carbon with hydrogen or by the hydrogenation of coal or itsproducts. In certain instances cracking coil tar fractions and coal taror shale oil distillates may also be used. Also for specialapplications, animal, vegetable or fish oils or their hydrogenated orvoltolized products may be employed in admixture with mineral oils.

For the best results the base stock chosen should normally be that oilwhich without the new additive present gives the optimum performance inthe service contemplated. However, since one advantage of the additivesis that their use also makes feasible the employment of lesssatisfactory mineral oils or other oils, no strict rule can be laid downfor the choice of the base stock. Certain essentials must of course beobserved. The oil must possess the viscosity and volatilitycharacteristics known to be required for the service contemplated. Theoil must be a satisfactory solvent for the additive, although in somecases 7 auxiliary solvent agents may be used. The lubricating oils,however they may have been produced, may vary considerably in viscosityand other properties depending upon the particular use for which theyare desired, but they usually range from about 40 to 150 secondsvSaybolt viscosity at 210 F. For the lubricating of certain low andmedium speed diesel engines the general practice has often been to use alubricating oil base stock prepared from naphthenic or aromatic crudesand having a Saybolt viscosity at 210 F. of 45 to 90 seconds and aviscosity index of to 50. However, in certain types of diesel engine andother gasoline engine service, oils of higher viscosity index are oftenpreferred, for example up to '75 to 100, or even higher, viscosityindex.

In addition to the materials to be added according to the presentinvention, other agents may also be used such as dyes, pour depressors,heat thickened fatty oils, sulfurized fatty oils, organometalliccompounds, metallic or other soaps, sludge dispersers, antioxidants,thickeners, viscosity index improvers, oiliness agents, resins, rubber,olefin polymers, voltolized fats, voltolized mineral oils, and/orvoltolized Waxes, and colloidal solids such as graphite or zinc oxide.Solvents and assisting agents, such as esters, ketones, alcohols,aldehydes, halogenated or nitrated compounds, and the like may also beemployed.

Assisting agents which are particularly desirable as plasticizers anddefoamers are the higher alcohols having eight or more carbon atoms andpreferably 12 to carbon atoms. The alcohols may be saturated straightand branched chain aliphatic alcohols such as octyl alcohol (CsHrIOI-I)lauryl alcohol (C12H25OH) cetyl alcohol (C1eH33OI-D, stearyl alcohol,sometimes referred to as octadecyl alcohol, (C1sI-I37OH), heptadecylalcohol (C17H35OH) and the like, the corresponding olefinic alcoholssuch as oleyl alcohol; cyclic alcohols such as naphthenic alcohols; andaryl substituted alkyl alcohols, for instance, phenyl octyl alcohol, oroctadecyl benzyl alcohol or mixtures of these various alcohols, whichmay be pure or substantially pure synthetic alcohols. One may also usemixed naturally occurring alcohols such as those found in Wool fat(which is known to contain a substantial percentage of alcohols havingabout 16 to 18 carbon atoms) and in sperm oil (which contains a highpercentage of cetyl alcohol); and although it is preferable to isolatethe alcohols from those materials, for

some purposes, the Wool fat, sperm oil or other natural products rich inalcohols may be used per se. Products prepared synthetically by chemicalprocesses may also be used, such as alcohols prepared by the oxidationof petroleum hydrocarbons, e. g., parafiin Wax, petrolatum, etc., and bythe OX0 reaction of olefins, carbon monoxide and hydrogen.

In addition to being employed in crankcase lubricants the additives ofthe present invention may also be used in extreme pressure lubricants,engine flushing oils, industrial oils, general machinery oils, processoils, rust preventive compositions, and greases.

The additives of the present invention may be employed as antioxidant orstabilizing agents not only in mineral lubricating oils, but also inhydrocarbon products generally, where improved resistance to oxidationis desired. Thus, the products may be added to motor oils, diesel fuels,kerosene, waxes, hydrocarbon polymers, natural and synthetic rubbers,and the like.

The present invention is not to be considered as limited by any of theexamples described herein, which are given by way of illustration only,but is to be limited solely by the terms of the appended claims.

What is claimed is:

1. As a new composition of matter an ester formed by reacting together adicyclic terpene and an organo-substituted acid of phosphorus of theformula:

where R is an alkyl hydrocarbon radical, said reaction involving aboutone mol of terpene to one mol of said acid of phosphorus.

2. As a new composition of matter an ester formed by reacting a pinenewith a di-alkyl thiophosphorous acid with suflicient heat to completethe reaction involving about one mol of said pinene and one mol of saidacid.

3. As a new composition of matter, the pinene ester of di-n-propylthiophosphorous acid prepared by heating together pinene and said acidwhereby substantially equal molar quantities of the pinene and acidreact.

4. The process which comprises heating together a di-cyclic terpene anda dialkyl thiophosphorous acid whereby substantially equal molarquantities of said terpene and said acid react.

5. The process which comprises heating together pinene and a di-alkylthiophosphorous acid whereby substantially equal molar quantities ofsaid pinene and said acid react.

6. The process which comprises heating together pinene and di-n-propylthiophosphorous acid whereby substantially equal molar quantities ofsaid pinene and said acid react.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,063,629 Salzberg Dec. 8, 1936 2,178,610 Salzberg Nov. 7,1939 2,266,514 Romieux Dec. 16, 1941 2,315,072 Nelson Mar. 30, 19432,381,377 Angel et al. Aug. 7, 1945 2,382,905 Pedersen Aug. 14, 1945

1. AS A NEW COMPOSITION OF MATTER AN ESTER FORMED BY REACTING TOGETHER ADICYCLIC TERPENE AND AN ORGANO-SUBSTITUTED ACID OF PHOSPHORUS OF THEFORMULA: